Today’s 3D printers make it fairly easy to conjure, say, a chess set into existence. But these printers are largely fixed in place. So if someone wants to add 3D-printed elements to a room—a footrest beneath a desk, for instance—the project gets more difficult. A space must be measured. The objects must then get scaled, printed elsewhere and fixed in the right spot. Handheld 3D printers exist, but they lack accuracy and come with a learning curve.